(1) Field of the Invention
The invention relates to an apparatus, and method for using such an apparatus, for managing coolant charge in air conditioning systems operating with a heat recovery mode.
(2) Description of the Related Art
In a typical air conditioning system, refrigerant flows from a compressor through condenser coils, and through an evaporator before returning to the compressor or compressors. The circuit thus formed, is referred to herein as a cooling circuit. Refrigerant travels around the cooling circuit when the air conditioning unit is in a cooling mode. By “cooling mode” it is meant that refrigerant is circulated through a cooling circuit to cool the air around the coils of the evaporator. Often times, there is provided a heat recovery circuit in parallel with the cooling circuit. The heat recovery circuit makes use of a heat recovery unit. The heat recovery unit is formed of a series of coils surrounded by water. When heated refrigerant travels through the coils, heat is transferred, or recovered, by the transference of the heat from the refrigerant to the surrounding water. Refrigerant travels through the heat recovery circuit during heat recovery mode. Typically, a valve or valves are closed to prohibit refrigerant from traveling through the heat recovery circuit during cooling mode. Conversely, a valve or valves are closed to prohibit the travel of refrigerant through the cooling circuit during heat recovery mode.
Because of the differing demands placed on the air conditioning system during cooling mode and heating mode, there exists a need for differing amounts of refrigerant circulating in the system. Specifically, during cooling mode, there is a need for a greater amount of refrigerant to travel through the cooling circuit. Conversely, during the heating mode, there is a lesser requirement for refrigerant traveling through the heat recovery circuit. What is therefore needed is a method of controlling the differing amounts of refrigerant required in the cooling mode and in the heat recovery mode that does not detract from the operation of the system, but rather uses the energy stored in the unneeded refrigerant to optimize the operation of the system in either mode.